Anatomy of the Temporomandibular Joint

Abstract

The part of the temporomandibular joint (TMJ) surface formed by the temporal squama is 25 (23–29) mm wide and 18.6 (13–23) mm long in our material (Hoffmann 1973). The rounded eminence of the articular tubercle of the temporal bone bounds the articular fossa from the front and helps to retain a normal occlusion and mastication. The articular disc of the TMJ, which moves forward when the mouth is opened, is 3–4 mm thick posteriorly, 1–2 mm thick centrally, and 1.5–2 mm thick anteriorly (where it apposes the articular eminence). A pars discosquamalis intervenes between the skull base and the articular disc, while a pars discomandibularis is placed between the articular disc and the head of the condyle. In the upper joint space, the articular surface facing the skull base has an area of 581 mm²; that facing the articular disc has an area of 501 mm². In the lower joint space, the articular surface on the disc side has a mean area of 396 mm²; on the mandibular side, 367 x¯ mm² (Lang and Niederfeilner 1975). The nerves of the TMJ are derived from the masseteric branches, the deep temporal branches, the auriculotemporal nerve, and in 50% of cases from the facial nerve (Guerrier and Bolönyi 1948; Kitamura 1974; Schmidt 1976; Thilander 1962; Moffet 1957; Oberbeckmann and Lautenbach 1979; etc.).